This is a group of approximately 15 projects entered into by several principal investigators. All of the problems concern cardiology as it is affected by operative techniques. The projects can be categorized into five groups: 1) Operative procedures for atherosclerotic heart disease. This is a group of projects investigating the value of operative techniques for the relief of angina and improvement in function in atherosclerotic and other forms of acquired heart disease. It studies the effect of interventions as well as the methods whereby these interventions are undertaken. 2) Cardiac transplantation. This is a group of studies to be conducted in the laboratory designed to detect early rejection and methods of preserving the heart. 3) Cardiac denervation. This is a group of studies undertaken to determine the effect of innervation on the heart and, therefore, also the effect of denervation, this being an accompaniment of cardiac transplantation. The consideration of sympathetic innervation of the heart complicates atherosclerotic disease, and myocardial infarction is studied by inducing ischemia in innervated and denervated hearts and assessing the difference between the two results. 4) The artificial heart. These are studies which assess isolated components of the artificial heart such as control mechanisms to regulate atrial pressure. 5) An assortment of other laboratory projects related to surgery of the heart. This is a group of eight projects which study the effects of drugs, operative procedures, and other operative interventions on the function of the heart and the capability of the experimental animal to survive such interventions. BIBLIOGRAPHIC REFERENCES: Kaiser GC, Marco JD, Barner HB, Codd JE, Laks H, Willman VL: Intra-aortic balloon assistance. Ann Thor Surg 21(6): 487-491, 1976. Laks H, Hahn JW, Standeven JW, Ott R, Willman VL: The left ventricular apical aortic assist heart transplant. Abstracts of the Am Assn Int Organs 5:46, 1976.